Validate APPEND custom commands more strictly

cmake/cmkr.cmake

@@ -10,7 +10,6 @@ if(CMAKE_SCRIPT_MODE_FILE)
     set(CMAKE_BINARY_DIR "${CMAKE_BINARY_DIR}/build")
     set(CMAKE_CURRENT_BINARY_DIR "${CMAKE_BINARY_DIR}")
     file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}")
-    file(WRITE "${CMAKE_BINARY_DIR}/.gitignore" "# This file is autogenerated by cmkr.\n*\n")
 endif()
 
 # Set these from the command line to customize for development/debugging purposes

docs/cmake-toml.md

@@ -199,6 +199,8 @@ tag = "v0.1"
 shallow = false # shallow clone (--depth 1)
 system = false
 subdir = "" # folder containing CMakeLists.txt
+# Set cache variables before FetchContent_MakeAvailable
+options = { BUILD_TESTS = false, BUILD_EXAMPLES = false }
 
 # Include a CMake project from a URL
 [fetch-content.urlcontent]
@@ -213,10 +215,19 @@ sha1 = "502a4e25b8b209889c99c7fa0732102682c2e4ff"
 condition = "mycondition"
 svn = "https://svn-host.com/url"
 rev = "svn_rev"
+
+# For many options, you can also use a separate table:
+# [fetch-content.bigproject.options]
+# BUILD_TESTS = false
+# BUILD_EXAMPLES = false
+# SOME_STRING_OPTION = "value"
+# SOME_LIST_OPTION = ["item1", "item2"]  # becomes "item1;item2"
 ```
 
 Table keys that match CMake variable names (`[A-Z_]+`) will be passed to the [`FetchContent_Declare`](https://cmake.org/cmake/help/latest/module/FetchContent.html#command:fetchcontent_declare) command.
 
+The `options` field allows setting CACHE variables before `FetchContent_MakeAvailable` is called. This is useful for configuring options on the fetched dependency (e.g., disabling tests). Boolean values become `ON`/`OFF`, arrays become semicolon-separated strings.
+
 ## Targets
 
 ```toml
@@ -246,6 +257,24 @@ link-options = [""] # linker flags
 private-link-options = [""]
 precompile-headers = [""] # precompiled headers
 private-precompile-headers = [""]
+dependencies = [""] # add_dependencies(target ...)
+
+# Keys below are for type = "custom" (add_custom_target)
+all = false
+command = ["${CMAKE_COMMAND}", "-E", "echo", "Hello"] # one command line
+commands = [ # multiple command lines
+    ["${CMAKE_COMMAND}", "-E", "echo", "First"],
+    ["${CMAKE_COMMAND}", "-E", "echo", "Second"],
+]
+depends = ["generated.txt"] # add_custom_target(... DEPENDS ...)
+byproducts = ["generated.txt"]
+working-directory = "${CMAKE_CURRENT_BINARY_DIR}"
+comment = "Run custom target"
+job-pool = "pool"
+job-server-aware = true
+verbatim = true
+uses-terminal = false # incompatible with job-pool when true
+command-expand-lists = true
 
 cmake-before = """
 message(STATUS "CMake injected before the target")
@@ -263,6 +292,51 @@ CXX_STANDARD_REQUIRED = true
 FOLDER = "MyFolder"
 ```
 
+### Custom commands
+
+Use `[[target.<name>.custom-command]]` to map directly to [`add_custom_command`](https://cmake.org/cmake/help/latest/command/add_custom_command.html). A custom command can use either the `OUTPUT` form or the `TARGET` form:
+
+```toml
+# OUTPUT form (add_custom_command(OUTPUT ...))
+[[target.mytarget.custom-command]]
+condition = "mycondition"
+outputs = ["generated.cpp"] # relative paths are interpreted from ${CMAKE_CURRENT_BINARY_DIR}
+command = [
+    "${CMAKE_COMMAND}",
+    "-DOUTPUT=${CMAKE_CURRENT_BINARY_DIR}/generated.cpp",
+    "-P",
+    "${CMAKE_CURRENT_SOURCE_DIR}/cmake/generate.cmake",
+]
+depends = ["cmake/generate.cmake"]
+byproducts = ["generated.hpp"]
+main-dependency = "cmake/generate.cmake"
+implicit-depends = [["CXX", "src/input.idl"]]
+working-directory = "${CMAKE_CURRENT_BINARY_DIR}"
+comment = "Generate source"
+depfile = "${CMAKE_CURRENT_BINARY_DIR}/generated.d"
+job-pool = "pool" # incompatible with uses-terminal when uses-terminal = true
+job-server-aware = true
+verbatim = true
+append = false
+uses-terminal = false
+codegen = false
+command-expand-lists = false
+depends-explicit-only = false
+
+# TARGET form (add_custom_command(TARGET ...))
+[[target.mytarget.custom-command]]
+build-event = "post-build" # pre-build, pre-link, post-build
+command = ["${CMAKE_COMMAND}", "-E", "touch", "${CMAKE_CURRENT_BINARY_DIR}/post-build.stamp"]
+byproducts = ["${CMAKE_CURRENT_BINARY_DIR}/post-build.stamp"]
+working-directory = "${CMAKE_CURRENT_BINARY_DIR}"
+comment = "Post-build step"
+verbatim = true
+command-expand-lists = false
+uses-terminal = false
+```
+
+For each custom command entry, exactly one of `outputs` or `build-event` is required. Relative `outputs`/`byproducts` paths follow CMake and are interpreted from the current binary directory. `build-event` is only valid for non-`interface` targets, and `pre-link` is not supported for `type = "custom"`. In both `add_custom_command(OUTPUT ...)` and `add_custom_target(...)`, `job-pool` cannot be combined with `uses-terminal = true`. When `append = true` is used with the `OUTPUT` form, at least one `command`/`commands` entry or `depends` must also be provided.
+
 A table mapping the cmkr features to the relevant CMake construct and the relevant documentation pages:
 
 | cmkr | CMake construct | Description |
@@ -279,6 +353,9 @@ A table mapping the cmkr features to the relevant CMake construct and the releva
 | `link-libraries` | [`target_link_libraries`](https://cmake.org/cmake/help/latest/command/target_link_libraries.html) | Adds library dependencies. Use `::mylib` to make sure a target exists. |
 | `link-options` | [`target_link_options`](https://cmake.org/cmake/help/latest/command/target_link_options.html) | Adds linker flags. |
 | `precompile-headers` | [`target_precompile_headers`](https://cmake.org/cmake/help/latest/command/target_precompile_headers.html) | Specifies precompiled headers. |
+| `dependencies` | [`add_dependencies`](https://cmake.org/cmake/help/latest/command/add_dependencies.html) | Adds target-level dependencies. |
+| `type = "custom"` + custom target keys | [`add_custom_target`](https://cmake.org/cmake/help/latest/command/add_custom_target.html) | Creates a custom target with command/dependency options. |
+| `[[target.<name>.custom-command]]` | [`add_custom_command`](https://cmake.org/cmake/help/latest/command/add_custom_command.html) | Supports both `OUTPUT` and `TARGET` forms. |
 | `properties` | [`set_target_properties`](https://cmake.org/cmake/help/latest/command/set_target_properties.html) | See [properties on targets](https://cmake.org/cmake/help/latest/manual/cmake-properties.7.html#properties-on-targets) for more information. |
 
 The default [visibility](/basics) is as follows:

docs/examples/custom-command.md

@@ -0,0 +1,141 @@
+---
+# Automatically generated from tests/custom-command/cmake.toml - DO NOT EDIT
+layout: default
+title: Tests add_custom_command and add_custom_target support
+permalink: /examples/custom-command
+parent: Examples
+nav_order: 12
+---
+
+# Tests add_custom_command and add_custom_target support
+
+This test demonstrates add_custom_command and add_custom_target support in cmkr.
+
+```toml
+#
+# There are two forms of add_custom_command in CMake:
+# 1. Output form: generates files that can be consumed by other targets
+# 2. Target form: runs commands at build time for a specific target (pre-build, pre-link, post-build)
+
+[project]
+name = "custom-command"
+description = "Tests add_custom_command and add_custom_target support"
+
+# -----------------------------------------------------------------------------
+# Simple executable demonstrating post-build events
+# -----------------------------------------------------------------------------
+
+[target.hello]
+type = "executable"
+sources = ["src/hello.cpp"]
+
+# This post-build command runs after the 'hello' executable is built.
+# build-event can be: "pre-build", "pre-link", or "post-build"
+[[target.hello.custom-command]]
+build-event = "post-build"
+command = ["${CMAKE_COMMAND}", "-E", "echo", "Built executable: $<TARGET_FILE_NAME:hello>"]
+comment = "Print the built executable name"
+
+# -----------------------------------------------------------------------------
+# Executable with code generation (output form custom command)
+# -----------------------------------------------------------------------------
+
+[target.custom-command]
+type = "executable"
+sources = ["src/main.cpp"]
+include-directories = ["${CMAKE_CURRENT_BINARY_DIR}/generated"]
+
+# Output form: This custom command generates source files before building.
+# Relative outputs follow CMake and are interpreted from the binary directory.
+# The outputs are automatically added as sources to the target.
+[[target.custom-command.custom-command]]
+outputs = ["generated/generated.cpp"]
+byproducts = ["generated/generated.hpp"]
+depends = ["cmake/generate_source.cmake"]
+command = [
+    "${CMAKE_COMMAND}",
+    "-DOUTPUT_CPP=${CMAKE_CURRENT_BINARY_DIR}/generated/generated.cpp",
+    "-DOUTPUT_HPP=${CMAKE_CURRENT_BINARY_DIR}/generated/generated.hpp",
+    "-P",
+    "${CMAKE_CURRENT_SOURCE_DIR}/cmake/generate_source.cmake",
+]
+comment = "Generate source files"
+verbatim = true
+
+# Target form: This post-build command runs after 'custom-command' is built.
+[[target.custom-command.custom-command]]
+build-event = "post-build"
+command = [
+    "${CMAKE_COMMAND}",
+    "-E",
+    "touch",
+    "${CMAKE_CURRENT_BINARY_DIR}/custom-command-post-build.stamp",
+]
+byproducts = ["${CMAKE_CURRENT_BINARY_DIR}/custom-command-post-build.stamp"]
+comment = "Create a post-build stamp file"
+verbatim = true
+
+# -----------------------------------------------------------------------------
+# Custom target (add_custom_target)
+# -----------------------------------------------------------------------------
+
+# A custom target runs commands independently of any executable/library.
+# Setting 'all = true' makes it run as part of the default build.
+[target.custom-codegen]
+type = "custom"
+all = true
+command = [
+    "${CMAKE_COMMAND}",
+    "-E",
+    "touch",
+    "${CMAKE_CURRENT_BINARY_DIR}/custom-target.stamp",
+]
+byproducts = ["${CMAKE_CURRENT_BINARY_DIR}/custom-target.stamp"]
+comment = "Run custom target"
+verbatim = true
+
+# -----------------------------------------------------------------------------
+# Template-based custom target
+# -----------------------------------------------------------------------------
+
+# Custom target options should also work when the target type comes from a template.
+[template.generated-custom-target]
+type = "custom"
+all = true
+verbatim = true
+
+[target.custom-codegen-template]
+type = "generated-custom-target"
+command = [
+    "${CMAKE_COMMAND}",
+    "-DINPUT=${CMAKE_CURRENT_BINARY_DIR}/template-custom-target.stamp",
+    "-P",
+    "${CMAKE_CURRENT_SOURCE_DIR}/cmake/verify_file_exists.cmake",
+]
+comment = "Verify the generated stamp exists"
+
+# The output-form custom command should automatically become a dependency of the
+# custom target, so the verification command sees the stamp file.
+[[target.custom-codegen-template.custom-command]]
+outputs = ["template-custom-target.stamp"]
+command = [
+    "${CMAKE_COMMAND}",
+    "-E",
+    "touch",
+    "${CMAKE_CURRENT_BINARY_DIR}/template-custom-target.stamp",
+]
+comment = "Create a stamp file for the template-based custom target"
+verbatim = true
+
+# A target-level all = false should override the template's all = true.
+# If this target is incorrectly included in the default build, the build fails.
+[target.custom-codegen-template-disabled]
+type = "generated-custom-target"
+all = false
+command = ["${CMAKE_COMMAND}", "-E", "false"]
+comment = "This target must not run as part of the default build"
+```
+
+
+
+<sup><sub>This page was automatically generated from [tests/custom-command/cmake.toml](https://github.com/build-cpp/cmkr/tree/main/tests/custom-command/cmake.toml).</sub></sup>

docs/examples/generator-executable.md

@@ -0,0 +1,74 @@
+---
+# Automatically generated from tests/generator-executable/cmake.toml - DO NOT EDIT
+layout: default
+title: Tests using an executable to generate sources for another target
+permalink: /examples/generator-executable
+parent: Examples
+nav_order: 13
+---
+
+# Tests using an executable to generate sources for another target
+
+This test demonstrates a common pattern: using an executable to generate sources
+
+for another target. The generator runs at build time and produces code that is
+
+consumed by the main executable.
+
+```toml
+#
+# CMake handles the dependency automatically: the generator executable is built
+# first, then it runs to produce the generated sources, and finally the main
+# executable is built using those sources.
+
+[project]
+name = "generator-executable"
+description = "Tests using an executable to generate sources for another target"
+
+# -----------------------------------------------------------------------------
+# Generator executable: produces code at build time
+# -----------------------------------------------------------------------------
+
+[target.generate_numbers]
+type = "executable"
+sources = ["src/generate_numbers.cpp"]
+
+# Post-build: confirm the generator was built
+[[target.generate_numbers.custom-command]]
+build-event = "post-build"
+command = ["${CMAKE_COMMAND}", "-E", "echo", "Generator built successfully: $<TARGET_FILE_NAME:generate_numbers>"]
+comment = "Confirm generator executable was built"
+
+# -----------------------------------------------------------------------------
+# Main executable: uses generated sources
+# -----------------------------------------------------------------------------
+
+[target.main]
+type = "executable"
+sources = ["src/main.cpp"]
+include-directories = ["${CMAKE_CURRENT_BINARY_DIR}/generated"]
+
+# Create the generated directory before the generator runs.
+cmake-before = """
+file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/generated")
+"""
+
+# Output form custom command: runs the generate_numbers executable to generate sources.
+# The outputs are automatically added as sources to this target.
+# The DEPENDS on "generate_numbers" ensures the generator is built before this runs.
+[[target.main.custom-command]]
+outputs = ["${CMAKE_CURRENT_BINARY_DIR}/generated/numbers.cpp"]
+depends = ["generate_numbers"]
+command = ["$<TARGET_FILE:generate_numbers>", "${CMAKE_CURRENT_BINARY_DIR}/generated/numbers.cpp"]
+comment = "Run generate_numbers to generate numbers.cpp"
+
+# Post-build: run the executable to verify it works
+[[target.main.custom-command]]
+build-event = "post-build"
+command = ["$<TARGET_FILE:main>"]
+comment = "Run the main executable to verify generated code works"
+```
+
+
+
+<sup><sub>This page was automatically generated from [tests/generator-executable/cmake.toml](https://github.com/build-cpp/cmkr/tree/main/tests/generator-executable/cmake.toml).</sub></sup>

docs/examples/protobuf.md

@@ -0,0 +1,99 @@
+---
+# Automatically generated from tests/protobuf/cmake.toml - DO NOT EDIT
+layout: default
+title: Demonstrates protobuf integration with cmkr custom commands
+permalink: /examples/protobuf
+parent: Examples
+nav_order: 14
+---
+
+# Demonstrates protobuf integration with cmkr custom commands
+
+This test demonstrates using protobuf with cmkr for code generation.
+
+```toml
+#
+# The example:
+# 1. Fetches protobuf from GitHub using FetchContent
+# 2. Uses a custom command to generate C++ sources from a .proto file
+# 3. Links an executable against the generated sources and protobuf library
+# 4. Serializes and deserializes a simple message
+#
+# Note: protobuf v21.x is used because newer versions (v22+) require abseil-cpp
+# as a dependency, which significantly complicates the build.
+
+[cmake]
+version = "3.18...3.31"
+
+[project]
+name = "protobuf-example"
+description = "Demonstrates protobuf integration with cmkr custom commands"
+
+# -----------------------------------------------------------------------------
+# Fetch protobuf from GitHub
+# Using v21.12 (last version before abseil-cpp became required)
+# -----------------------------------------------------------------------------
+
+[fetch-content.protobuf]
+git = "https://github.com/protocolbuffers/protobuf"
+tag = "v21.12"
+options = {
+  protobuf_BUILD_TESTS = false,
+  protobuf_BUILD_EXAMPLES = false,
+  protobuf_BUILD_LIBPROTOC = false,
+  protobuf_BUILD_SHARED_LIBS = false,
+  protobuf_MSVC_STATIC_RUNTIME = false,
+  SKIP_INSTALL_ALL = true,
+  protobuf_WITH_ZLIB = false,
+}
+
+# -----------------------------------------------------------------------------
+# Main executable using protobuf
+# -----------------------------------------------------------------------------
+
+[target.protobuf_example]
+type = "executable"
+sources = [
+    "src/main.cpp",
+]
+include-directories = [
+    "${CMAKE_CURRENT_BINARY_DIR}/generated",
+]
+link-libraries = ["protobuf::libprotobuf"]
+compile-features = ["cxx_std_17"]
+
+# Create the generated directory before running protoc
+cmake-before = """
+file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/generated")
+"""
+
+# Custom command to generate C++ sources from .proto file
+# This uses protoc from the fetched protobuf repository
+[[target.protobuf_example.custom-command]]
+outputs = [
+    "${CMAKE_CURRENT_BINARY_DIR}/generated/addressbook.pb.h",
+    "${CMAKE_CURRENT_BINARY_DIR}/generated/addressbook.pb.cc",
+]
+depends = [
+    "${CMAKE_CURRENT_SOURCE_DIR}/proto/addressbook.proto",
+    "protobuf::protoc",  # Ensure protoc is built first
+]
+command = [
+    "$<TARGET_FILE:protobuf::protoc>",
+    "--cpp_out=${CMAKE_CURRENT_BINARY_DIR}/generated",
+    "-I${CMAKE_CURRENT_SOURCE_DIR}/proto",
+    "${CMAKE_CURRENT_SOURCE_DIR}/proto/addressbook.proto",
+]
+comment = "Generate C++ sources from addressbook.proto"
+verbatim = true
+
+# Post-build: run the executable to verify it works
+[[target.protobuf_example.custom-command]]
+build-event = "post-build"
+command = ["$<TARGET_FILE:protobuf_example>"]
+comment = "Run protobuf_example to verify serialization/deserialization works"
+```
+
+
+
+<sup><sub>This page was automatically generated from [tests/protobuf/cmake.toml](https://github.com/build-cpp/cmkr/tree/main/tests/protobuf/cmake.toml).</sub></sup>

include/project_parser.hpp

@@ -74,6 +74,104 @@ enum TargetType {
 extern const char *targetTypeNames[target_last];
 
 struct Target {
+    struct CustomTarget {
+        bool has_all = false;
+        bool all = false;
+
+        bool has_command = false;
+        bool has_commands = false;
+        std::vector<std::vector<std::string>> commands;
+        std::vector<std::string> depends;
+        std::vector<std::string> byproducts;
+
+        bool has_working_directory = false;
+        std::string working_directory;
+
+        bool has_comment = false;
+        std::string comment;
+
+        bool has_job_pool = false;
+        std::string job_pool;
+
+        bool has_job_server_aware = false;
+        bool job_server_aware = false;
+
+        bool has_verbatim = false;
+        bool verbatim = false;
+
+        bool has_uses_terminal = false;
+        bool uses_terminal = false;
+
+        bool has_command_expand_lists = false;
+        bool command_expand_lists = false;
+
+        bool empty() const {
+            return !has_all && !has_command && !has_commands && commands.empty() && depends.empty() && byproducts.empty() && !has_working_directory &&
+                   !has_comment && !has_job_pool && !has_job_server_aware && !has_verbatim && !has_uses_terminal && !has_command_expand_lists;
+        }
+    };
+
+    struct CustomCommand {
+        struct ImplicitDependency {
+            std::string language;
+            std::string file;
+        };
+
+        std::string condition;
+        std::vector<std::vector<std::string>> commands;
+
+        std::vector<std::string> outputs;
+        std::string build_event;
+
+        bool has_append = false;
+        bool append = false;
+
+        bool has_main_dependency = false;
+        std::string main_dependency;
+
+        std::vector<std::string> depends;
+        std::vector<std::string> byproducts;
+        std::vector<ImplicitDependency> implicit_depends;
+
+        bool has_working_directory = false;
+        std::string working_directory;
+
+        bool has_comment = false;
+        std::string comment;
+
+        bool has_depfile = false;
+        std::string depfile;
+
+        bool has_job_pool = false;
+        std::string job_pool;
+
+        bool has_job_server_aware = false;
+        bool job_server_aware = false;
+
+        bool has_verbatim = false;
+        bool verbatim = false;
+
+        bool has_uses_terminal = false;
+        bool uses_terminal = false;
+
+        bool has_codegen = false;
+        bool codegen = false;
+
+        bool has_command_expand_lists = false;
+        bool command_expand_lists = false;
+
+        bool has_depends_explicit_only = false;
+        bool depends_explicit_only = false;
+
+        bool is_output_form() const {
+            return !outputs.empty();
+        }
+
+        bool is_target_form() const {
+            return !build_event.empty();
+        }
+    };
+
     std::string name;
     TargetType type = target_last;
     std::string type_name;
@@ -107,6 +205,9 @@ struct Target {
 
     ConditionVector dependencies;
 
+    CustomTarget custom_target;
+    std::vector<CustomCommand> custom_commands;
+
     std::string condition;
     std::string alias;
     Condition<tsl::ordered_map<std::string, std::string>> properties;
@@ -154,10 +255,15 @@ struct Subdir {
     ConditionVector include_after;
 };
 
+struct ContentOption {
+    mpark::variant<bool, std::string> value;
+};
+
 struct Content {
     std::string name;
     std::string condition;
     tsl::ordered_map<std::string, std::string> arguments;
+    tsl::ordered_map<std::string, ContentOption> options;
 
     Condition<std::string> cmake_before;
     Condition<std::string> cmake_after;

src/cmake_generator.cpp

@@ -4,6 +4,7 @@
 
 #include "fs.hpp"
 #include "project_parser.hpp"
+#include <algorithm>
 #include <cstdio>
 #include <memory>
 #include <sstream>
@@ -1123,6 +1124,22 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
             gen.conditional_includes(content.include_before);
             gen.conditional_cmake(content.cmake_before);
 
+            // Set cache variables before FetchContent
+            if (!content.options.empty()) {
+                for (const auto &opt : content.options) {
+                    std::string value;
+                    std::string type;
+                    if (opt.second.value.index() == 0) {
+                        value = mpark::get<0>(opt.second.value) ? "ON" : "OFF";
+                        type = "BOOL";
+                    } else {
+                        value = mpark::get<1>(opt.second.value);
+                        type = "STRING";
+                    }
+                    cmd("set")(opt.first, value, "CACHE", type, RawArg("\"\""), "FORCE");
+                }
+            }
+
             std::string version_info;
             if (content.arguments.contains("GIT_TAG")) {
                 version_info = " (" + content.arguments.at("GIT_TAG") + ")";
@@ -1205,6 +1222,14 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                 }
             }
 
+            auto resolved_target_type = target.type;
+            if (tmplate != nullptr) {
+                if (resolved_target_type != parser::target_template) {
+                    throw_target_error("Unreachable code, unexpected target type for template");
+                }
+                resolved_target_type = tmplate->outline.type;
+            }
+
             ConditionScope cs(gen, target.condition);
 
             // Detect if there is cmake included before/after the target
@@ -1244,6 +1269,103 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
             gen.conditional_includes(target.include_before);
             gen.conditional_cmake(target.cmake_before);
 
+            auto merge_unique_vector = [](std::vector<std::string> &destination, const std::vector<std::string> &source) {
+                for (const auto &item : source) {
+                    if (std::find(destination.begin(), destination.end(), item) == destination.end()) {
+                        destination.push_back(item);
+                    }
+                }
+            };
+
+            auto custom_target = target.custom_target;
+            if (tmplate != nullptr) {
+                const auto &custom = tmplate->outline.custom_target;
+                if (!custom_target.has_all && custom.has_all) {
+                    custom_target.has_all = true;
+                    custom_target.all = custom.all;
+                }
+                if (custom.has_command) {
+                    custom_target.has_command = true;
+                }
+                if (custom.has_commands) {
+                    custom_target.has_commands = true;
+                }
+                if (!custom.commands.empty()) {
+                    custom_target.commands.insert(custom_target.commands.begin(), custom.commands.begin(), custom.commands.end());
+                }
+                merge_unique_vector(custom_target.depends, custom.depends);
+                merge_unique_vector(custom_target.byproducts, custom.byproducts);
+                if (!custom_target.has_working_directory && custom.has_working_directory) {
+                    custom_target.has_working_directory = true;
+                    custom_target.working_directory = custom.working_directory;
+                }
+                if (!custom_target.has_comment && custom.has_comment) {
+                    custom_target.has_comment = true;
+                    custom_target.comment = custom.comment;
+                }
+                if (!custom_target.has_job_pool && custom.has_job_pool) {
+                    custom_target.has_job_pool = true;
+                    custom_target.job_pool = custom.job_pool;
+                }
+                if (!custom_target.has_job_server_aware && custom.has_job_server_aware) {
+                    custom_target.has_job_server_aware = true;
+                    custom_target.job_server_aware = custom.job_server_aware;
+                }
+                if (!custom_target.has_verbatim && custom.has_verbatim) {
+                    custom_target.has_verbatim = true;
+                    custom_target.verbatim = custom.verbatim;
+                }
+                if (!custom_target.has_uses_terminal && custom.has_uses_terminal) {
+                    custom_target.has_uses_terminal = true;
+                    custom_target.uses_terminal = custom.uses_terminal;
+                }
+                if (!custom_target.has_command_expand_lists && custom.has_command_expand_lists) {
+                    custom_target.has_command_expand_lists = true;
+                    custom_target.command_expand_lists = custom.command_expand_lists;
+                }
+            }
+
+            std::vector<parser::Target::CustomCommand> custom_commands;
+            if (tmplate != nullptr) {
+                custom_commands.insert(custom_commands.end(), tmplate->outline.custom_commands.begin(), tmplate->outline.custom_commands.end());
+            }
+            custom_commands.insert(custom_commands.end(), target.custom_commands.begin(), target.custom_commands.end());
+
+            if (resolved_target_type == parser::target_custom && custom_target.has_job_pool && custom_target.has_uses_terminal &&
+                custom_target.uses_terminal) {
+                throw_target_error("job-pool cannot be used with uses-terminal");
+            }
+
+            auto has_cmake_path_reference = [](const std::string &value) {
+                return value.find("${") != std::string::npos || value.find("$ENV{") != std::string::npos ||
+                       value.find("$CACHE{") != std::string::npos;
+            };
+
+            auto normalize_generated_output_source = [&has_cmake_path_reference](const std::string &output) {
+                auto starts_with = [](const std::string &value, const std::string &prefix) {
+                    return value.rfind(prefix, 0) == 0;
+                };
+                if (fs::path(output).is_absolute()) {
+                    return output;
+                }
+                if (starts_with(output, "${CMAKE_CURRENT_BINARY_DIR}") || starts_with(output, "${CMAKE_BINARY_DIR}") ||
+                    starts_with(output, "${PROJECT_BINARY_DIR}") || starts_with(output, "${CMAKE_CURRENT_SOURCE_DIR}") ||
+                    starts_with(output, "${CMAKE_SOURCE_DIR}") || starts_with(output, "${PROJECT_SOURCE_DIR}") ||
+                    starts_with(output, "${CMAKE_CURRENT_LIST_DIR}") || starts_with(output, "$ENV{") || starts_with(output, "$CACHE{") ||
+                    has_cmake_path_reference(output)) {
+                    return output;
+                }
+                return "${CMAKE_CURRENT_BINARY_DIR}/" + output;
+            };
+
+            parser::Condition<tsl::ordered_set<std::string>> mcustom_target_depends;
+            if (resolved_target_type == parser::target_custom) {
+                auto &unconditional_depends = mcustom_target_depends[""];
+                for (const auto &dep : custom_target.depends) {
+                    unconditional_depends.insert(dep);
+                }
+            }
+
             // Merge the sources from the template and the target. The sources
             // without condition need to be processed first
             parser::Condition<tsl::ordered_set<std::string>> msources;
@@ -1262,8 +1384,21 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
             }
             merge_sources(target.sources);
 
+            for (const auto &custom_command : custom_commands) {
+                if (!custom_command.is_output_form()) {
+                    continue;
+                }
+                auto &condition_sources = msources[custom_command.condition];
+                for (const auto &output : custom_command.outputs) {
+                    condition_sources.insert(normalize_generated_output_source(output));
+                    if (resolved_target_type == parser::target_custom) {
+                        mcustom_target_depends[custom_command.condition].insert(output);
+                    }
+                }
+            }
+
             // Improve IDE support
-            if (target.type != parser::target_interface) {
+            if (resolved_target_type != parser::target_interface) {
                 msources[""].insert("cmake.toml");
             }
 
@@ -1297,7 +1432,7 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                 }
 
                 // Make sure there are source files for the languages used by the project
-                switch (target.type) {
+                switch (resolved_target_type) {
                 case parser::target_executable:
                 case parser::target_library:
                 case parser::target_shared:
@@ -1316,8 +1451,7 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
 
                     // Make sure relative source files exist
                     for (const auto &source : sources) {
-                        auto var_index = source.find("${");
+                        if (has_cmake_path_reference(source))
-                        if (var_index != std::string::npos)
                             continue;
                         const auto &source_path = fs::path(path) / source;
                         if (!fs::exists(source_path)) {
@@ -1341,18 +1475,12 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                 }
             });
 
-            auto target_type = target.type;
+            auto target_type = resolved_target_type;
-
-            if (tmplate != nullptr) {
-                if (target_type != parser::target_template) {
-                    throw_target_error("Unreachable code, unexpected target type for template");
-                }
-                target_type = tmplate->outline.type;
-            }
 
             std::string add_command;
             std::string target_type_string;
             std::string target_scope;
+            bool is_custom_target = false;
 
             switch (target_type) {
             case parser::target_executable:
@@ -1381,9 +1509,7 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                 target_scope = "INTERFACE";
                 break;
             case parser::target_custom:
-                // TODO: add proper support, this is hacky
+                is_custom_target = true;
-                add_command = "add_custom_target";
-                target_type_string = "SOURCES";
                 target_scope = "PUBLIC";
                 break;
             case parser::target_object:
@@ -1396,6 +1522,157 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                 throw_target_error("Unimplemented enum value");
             }
 
+            auto has_custom_target_depends = false;
+            auto custom_target_depends_var = target.name + "_DEPENDS";
+            auto custom_target_depends_with_set = true;
+            if (is_custom_target) {
+                for (const auto &itr : mcustom_target_depends) {
+                    if (!itr.second.empty()) {
+                        has_custom_target_depends = true;
+                        break;
+                    }
+                }
+                if (has_custom_target_depends && mcustom_target_depends[""].empty()) {
+                    custom_target_depends_with_set = false;
+                    cmd("set")(custom_target_depends_var, RawArg("\"\"")).endl();
+                }
+                gen.handle_condition(mcustom_target_depends, [&](const std::string &condition, const tsl::ordered_set<std::string> &depend_set) {
+                    std::vector<std::string> depends;
+                    depends.reserve(depend_set.size());
+                    for (const auto &depend : depend_set) {
+                        depends.push_back(depend);
+                    }
+
+                    if (custom_target_depends_with_set) {
+                        if (!condition.empty()) {
+                            throw_target_error("Unreachable code, make sure unconditional depends are first");
+                        }
+                        cmd("set")(custom_target_depends_var, depends);
+                        custom_target_depends_with_set = false;
+                    } else {
+                        cmd("list")("APPEND", custom_target_depends_var, depends);
+                    }
+                });
+            }
+
+            auto append_keyword = [](std::vector<RawArg> &args, const std::string &keyword) {
+                args.emplace_back(keyword);
+            };
+            auto append_value = [](std::vector<RawArg> &args, const std::string &value) {
+                args.emplace_back(Command::quote(value));
+            };
+            auto append_values = [&](std::vector<RawArg> &args, const std::vector<std::string> &values) {
+                for (const auto &value : values) {
+                    append_value(args, value);
+                }
+            };
+            auto append_commands = [&](std::vector<RawArg> &args, const std::vector<std::vector<std::string>> &commands) {
+                for (const auto &command_args : commands) {
+                    append_keyword(args, "COMMAND");
+                    append_values(args, command_args);
+                }
+            };
+
+            auto emit_custom_command = [&](const parser::Target::CustomCommand &custom_command) {
+                std::vector<RawArg> args;
+                if (custom_command.is_output_form()) {
+                    append_keyword(args, "OUTPUT");
+                    append_values(args, custom_command.outputs);
+                    append_commands(args, custom_command.commands);
+                    if (custom_command.has_main_dependency) {
+                        append_keyword(args, "MAIN_DEPENDENCY");
+                        append_value(args, custom_command.main_dependency);
+                    }
+                    if (!custom_command.depends.empty()) {
+                        append_keyword(args, "DEPENDS");
+                        append_values(args, custom_command.depends);
+                    }
+                    if (!custom_command.byproducts.empty()) {
+                        append_keyword(args, "BYPRODUCTS");
+                        append_values(args, custom_command.byproducts);
+                    }
+                    if (!custom_command.implicit_depends.empty()) {
+                        append_keyword(args, "IMPLICIT_DEPENDS");
+                        for (const auto &implicit_dependency : custom_command.implicit_depends) {
+                            append_value(args, implicit_dependency.language);
+                            append_value(args, implicit_dependency.file);
+                        }
+                    }
+                    if (custom_command.has_working_directory) {
+                        append_keyword(args, "WORKING_DIRECTORY");
+                        append_value(args, custom_command.working_directory);
+                    }
+                    if (custom_command.has_comment) {
+                        append_keyword(args, "COMMENT");
+                        append_value(args, custom_command.comment);
+                    }
+                    if (custom_command.has_depfile) {
+                        append_keyword(args, "DEPFILE");
+                        append_value(args, custom_command.depfile);
+                    }
+                    if (custom_command.has_job_pool) {
+                        append_keyword(args, "JOB_POOL");
+                        append_value(args, custom_command.job_pool);
+                    }
+                    if (custom_command.has_job_server_aware) {
+                        append_keyword(args, "JOB_SERVER_AWARE");
+                        append_value(args, custom_command.job_server_aware ? "ON" : "OFF");
+                    }
+                    if (custom_command.has_verbatim && custom_command.verbatim) {
+                        append_keyword(args, "VERBATIM");
+                    }
+                    if (custom_command.has_append && custom_command.append) {
+                        append_keyword(args, "APPEND");
+                    }
+                    if (custom_command.has_uses_terminal && custom_command.uses_terminal) {
+                        append_keyword(args, "USES_TERMINAL");
+                    }
+                    if (custom_command.has_codegen && custom_command.codegen) {
+                        append_keyword(args, "CODEGEN");
+                    }
+                    if (custom_command.has_command_expand_lists && custom_command.command_expand_lists) {
+                        append_keyword(args, "COMMAND_EXPAND_LISTS");
+                    }
+                    if (custom_command.has_depends_explicit_only && custom_command.depends_explicit_only) {
+                        append_keyword(args, "DEPENDS_EXPLICIT_ONLY");
+                    }
+                } else {
+                    append_keyword(args, "TARGET");
+                    append_value(args, target.name);
+                    append_keyword(args, custom_command.build_event);
+                    append_commands(args, custom_command.commands);
+                    if (!custom_command.byproducts.empty()) {
+                        append_keyword(args, "BYPRODUCTS");
+                        append_values(args, custom_command.byproducts);
+                    }
+                    if (custom_command.has_working_directory) {
+                        append_keyword(args, "WORKING_DIRECTORY");
+                        append_value(args, custom_command.working_directory);
+                    }
+                    if (custom_command.has_comment) {
+                        append_keyword(args, "COMMENT");
+                        append_value(args, custom_command.comment);
+                    }
+                    if (custom_command.has_verbatim && custom_command.verbatim) {
+                        append_keyword(args, "VERBATIM");
+                    }
+                    if (custom_command.has_command_expand_lists && custom_command.command_expand_lists) {
+                        append_keyword(args, "COMMAND_EXPAND_LISTS");
+                    }
+                    if (custom_command.has_uses_terminal && custom_command.uses_terminal) {
+                        append_keyword(args, "USES_TERMINAL");
+                    }
+                }
+                cmd("add_custom_command")(args).endl();
+            };
+
+            for (const auto &custom_command : custom_commands) {
+                if (custom_command.is_output_form()) {
+                    ConditionScope custom_scope(gen, custom_command.condition);
+                    emit_custom_command(custom_command);
+                }
+            }
+
             // Handle custom add commands from templates.
             if (tmplate != nullptr && !tmplate->add_function.empty()) {
                 add_command = tmplate->add_function;
@@ -1409,6 +1686,51 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                                               "${" + sources_var + "}");
                     }
                 }
+            } else if (is_custom_target) {
+                std::vector<RawArg> args;
+                append_value(args, target.name);
+                if (custom_target.has_all && custom_target.all) {
+                    append_keyword(args, "ALL");
+                }
+                append_commands(args, custom_target.commands);
+                if (has_custom_target_depends) {
+                    append_keyword(args, "DEPENDS");
+                    append_value(args, "${" + custom_target_depends_var + "}");
+                }
+                if (!custom_target.byproducts.empty()) {
+                    append_keyword(args, "BYPRODUCTS");
+                    append_values(args, custom_target.byproducts);
+                }
+                if (custom_target.has_working_directory) {
+                    append_keyword(args, "WORKING_DIRECTORY");
+                    append_value(args, custom_target.working_directory);
+                }
+                if (custom_target.has_comment) {
+                    append_keyword(args, "COMMENT");
+                    append_value(args, custom_target.comment);
+                }
+                if (custom_target.has_job_pool) {
+                    append_keyword(args, "JOB_POOL");
+                    append_value(args, custom_target.job_pool);
+                }
+                if (custom_target.has_job_server_aware) {
+                    append_keyword(args, "JOB_SERVER_AWARE");
+                    append_value(args, custom_target.job_server_aware ? "ON" : "OFF");
+                }
+                if (custom_target.has_verbatim && custom_target.verbatim) {
+                    append_keyword(args, "VERBATIM");
+                }
+                if (custom_target.has_uses_terminal && custom_target.uses_terminal) {
+                    append_keyword(args, "USES_TERMINAL");
+                }
+                if (custom_target.has_command_expand_lists && custom_target.command_expand_lists) {
+                    append_keyword(args, "COMMAND_EXPAND_LISTS");
+                }
+                if (has_sources) {
+                    append_keyword(args, "SOURCES");
+                    append_value(args, "${" + sources_var + "}");
+                }
+                cmd("add_custom_target")(args).endl();
             } else {
                 cmd(add_command)(target.name, target_type_string).endl();
                 if (has_sources) {
@@ -1416,6 +1738,13 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
                 }
             }
 
+            for (const auto &custom_command : custom_commands) {
+                if (custom_command.is_target_form()) {
+                    ConditionScope custom_scope(gen, custom_command.condition);
+                    emit_custom_command(custom_command);
+                }
+            }
+
             // TODO: support sources from other directories
             if (has_sources) {
                 cmd("source_group")("TREE", "${CMAKE_CURRENT_SOURCE_DIR}", "FILES", "${" + sources_var + "}").endl();
@@ -1452,29 +1781,31 @@ void generate_cmake(const char *path, const parser::Project *parent_project) {
             };
 
             auto gen_target_cmds = [&](const parser::Target &t) {
-                target_cmd("target_compile_definitions", t.compile_definitions, target_scope);
+                if (!is_custom_target) {
-                target_cmd("target_compile_definitions", t.private_compile_definitions, "PRIVATE");
+                    target_cmd("target_compile_definitions", t.compile_definitions, target_scope);
+                    target_cmd("target_compile_definitions", t.private_compile_definitions, "PRIVATE");
 
-                target_cmd("target_compile_features", t.compile_features, target_scope);
+                    target_cmd("target_compile_features", t.compile_features, target_scope);
-                target_cmd("target_compile_features", t.private_compile_features, "PRIVATE");
+                    target_cmd("target_compile_features", t.private_compile_features, "PRIVATE");
 
-                target_cmd("target_compile_options", t.compile_options, target_scope);
+                    target_cmd("target_compile_options", t.compile_options, target_scope);
-                target_cmd("target_compile_options", t.private_compile_options, "PRIVATE");
+                    target_cmd("target_compile_options", t.private_compile_options, "PRIVATE");
 
-                target_cmd("target_include_directories", t.include_directories, target_scope);
+                    target_cmd("target_include_directories", t.include_directories, target_scope);
-                target_cmd("target_include_directories", t.private_include_directories, "PRIVATE");
+                    target_cmd("target_include_directories", t.private_include_directories, "PRIVATE");
 
-                target_cmd("target_link_directories", t.link_directories, target_scope);
+                    target_cmd("target_link_directories", t.link_directories, target_scope);
-                target_cmd("target_link_directories", t.private_link_directories, "PRIVATE");
+                    target_cmd("target_link_directories", t.private_link_directories, "PRIVATE");
 
-                link_cmd("target_link_libraries", t.link_libraries, target_scope);
+                    link_cmd("target_link_libraries", t.link_libraries, target_scope);
-                link_cmd("target_link_libraries", t.private_link_libraries, "PRIVATE");
+                    link_cmd("target_link_libraries", t.private_link_libraries, "PRIVATE");
 
-                target_cmd("target_link_options", t.link_options, target_scope);
+                    target_cmd("target_link_options", t.link_options, target_scope);
-                target_cmd("target_link_options", t.private_link_options, "PRIVATE");
+                    target_cmd("target_link_options", t.private_link_options, "PRIVATE");
 
-                target_cmd("target_precompile_headers", t.precompile_headers, target_scope);
+                    target_cmd("target_precompile_headers", t.precompile_headers, target_scope);
-                target_cmd("target_precompile_headers", t.private_precompile_headers, "PRIVATE");
+                    target_cmd("target_precompile_headers", t.private_precompile_headers, "PRIVATE");
+                }
 
                 link_cmd("add_dependencies", t.dependencies, "");
             };

src/project_parser.cpp

@@ -1,6 +1,7 @@
 #include "project_parser.hpp"
 
 #include "fs.hpp"
+#include <cctype>
 #include <deque>
 #include <stdexcept>
 #include <toml.hpp>
@@ -209,6 +210,105 @@ class TomlCheckerRoot {
     }
 };
 
+static std::vector<std::string> parse_string_array(const TomlBasicValue &value, const toml::key &key) {
+    if (!value.is_array()) {
+        throw_key_error("Expected an array", key, value);
+    }
+    std::vector<std::string> values;
+    for (const auto &entry : value.as_array()) {
+        if (!entry.is_string()) {
+            throw_key_error("Expected an array of strings", key, entry);
+        }
+        values.push_back(entry.as_string());
+    }
+    return values;
+}
+
+static std::vector<std::vector<std::string>> parse_command_arguments(const TomlBasicValue &value, const toml::key &key) {
+    if (!value.is_array()) {
+        throw_key_error("Expected an array", key, value);
+    }
+    const auto &array = value.as_array();
+    if (array.empty()) {
+        return {};
+    }
+
+    bool all_strings = true;
+    bool all_arrays = true;
+    for (const auto &entry : array) {
+        if (!entry.is_string()) {
+            all_strings = false;
+        }
+        if (!entry.is_array()) {
+            all_arrays = false;
+        }
+    }
+
+    std::vector<std::vector<std::string>> commands;
+    if (all_strings) {
+        commands.push_back(parse_string_array(value, key));
+        if (commands[0].empty()) {
+            throw_key_error("Command arrays cannot be empty", key, value);
+        }
+        return commands;
+    }
+
+    if (!all_arrays) {
+        throw_key_error("Expected an array of command arrays", key, value);
+    }
+
+    for (const auto &entry : array) {
+        auto command = parse_string_array(entry, key);
+        if (command.empty()) {
+            throw_key_error("Command arrays cannot be empty", key, entry);
+        }
+        commands.push_back(std::move(command));
+    }
+
+    return commands;
+}
+
+static std::vector<Target::CustomCommand::ImplicitDependency> parse_implicit_dependencies(const TomlBasicValue &value, const toml::key &key) {
+    if (!value.is_array()) {
+        throw_key_error("Expected an array", key, value);
+    }
+    std::vector<Target::CustomCommand::ImplicitDependency> implicit_dependencies;
+    for (const auto &entry : value.as_array()) {
+        auto values = parse_string_array(entry, key);
+        if (values.size() != 2) {
+            throw_key_error("Each implicit dependency must have exactly two strings: [language, file]", key, entry);
+        }
+        Target::CustomCommand::ImplicitDependency implicit_dependency;
+        implicit_dependency.language = std::move(values[0]);
+        implicit_dependency.file = std::move(values[1]);
+        implicit_dependencies.push_back(std::move(implicit_dependency));
+    }
+    return implicit_dependencies;
+}
+
+static std::string normalize_build_event(std::string build_event) {
+    for (auto &ch : build_event) {
+        if (ch == '-') {
+            ch = '_';
+        } else {
+            ch = static_cast<char>(std::toupper(static_cast<unsigned char>(ch)));
+        }
+    }
+    return build_event;
+}
+
+static TargetType resolve_target_type(const Target &target, const std::vector<Template> &templates) {
+    if (target.type != target_template) {
+        return target.type;
+    }
+    for (const auto &tmplate : templates) {
+        if (target.type_name == tmplate.outline.name) {
+            return tmplate.outline.type;
+        }
+    }
+    return target.type;
+}
+
 Project::Project(const Project *parent, const std::string &path, bool build) : parent(parent) {
     const auto toml_path = fs::path(path) / "cmake.toml";
     if (!fs::exists(toml_path)) {
@@ -505,7 +605,37 @@ Project::Project(const Project *parent, const std::string &path, bool build) : p
                                 "system", "");
             }
 
+            // Parse options table - these are CACHE variables set before FetchContent
+            if (c.contains("options")) {
+                c.visit("options");
+                const auto &opts = toml::find(itr.second, "options").as_table();
+                for (const auto &optItr : opts) {
+                    ContentOption opt;
+                    if (optItr.second.is_boolean()) {
+                        opt.value = optItr.second.as_boolean();
+                    } else if (optItr.second.is_array()) {
+                        // Arrays become semicolon-separated lists
+                        std::string list_value;
+                        for (const auto &list_val : optItr.second.as_array()) {
+                            if (!list_value.empty()) {
+                                list_value += ';';
+                            }
+                            list_value += list_val.as_string();
+                        }
+                        opt.value = list_value;
+                    } else {
+                        opt.value = optItr.second.as_string();
+                    }
+                    content.options.emplace(optItr.first, opt);
+                }
+            }
+
             for (const auto &argItr : itr.second.as_table()) {
+                // Skip keys that were already handled (like "options")
+                if (c.visisted(argItr.first)) {
+                    continue;
+                }
+
                 std::string value;
                 if (argItr.second.is_array()) {
                     for (const auto &list_val : argItr.second.as_array()) {
@@ -698,6 +828,253 @@ Project::Project(const Project *parent, const std::string &path, bool build) : p
 
         t.optional("dependencies", target.dependencies);
 
+        const auto resolved_target_type = resolve_target_type(target, templates);
+
+        if (t.contains("all")) {
+            target.custom_target.has_all = true;
+            target.custom_target.all = t.find("all").as_boolean();
+        }
+
+        if (t.contains("command")) {
+            target.custom_target.has_command = true;
+            auto commands = parse_command_arguments(t.find("command"), "command");
+            for (auto &command : commands) {
+                target.custom_target.commands.push_back(std::move(command));
+            }
+        }
+
+        if (t.contains("commands")) {
+            target.custom_target.has_commands = true;
+            auto commands = parse_command_arguments(t.find("commands"), "commands");
+            for (auto &command : commands) {
+                target.custom_target.commands.push_back(std::move(command));
+            }
+        }
+
+        t.optional("depends", target.custom_target.depends);
+        t.optional("byproducts", target.custom_target.byproducts);
+
+        if (t.contains("working-directory")) {
+            target.custom_target.has_working_directory = true;
+            target.custom_target.working_directory = t.find("working-directory").as_string();
+        }
+
+        if (t.contains("comment")) {
+            target.custom_target.has_comment = true;
+            target.custom_target.comment = t.find("comment").as_string();
+        }
+
+        if (t.contains("job-pool")) {
+            target.custom_target.has_job_pool = true;
+            target.custom_target.job_pool = t.find("job-pool").as_string();
+        }
+
+        if (t.contains("job-server-aware")) {
+            target.custom_target.has_job_server_aware = true;
+            target.custom_target.job_server_aware = t.find("job-server-aware").as_boolean();
+        }
+
+        if (t.contains("verbatim")) {
+            target.custom_target.has_verbatim = true;
+            target.custom_target.verbatim = t.find("verbatim").as_boolean();
+        }
+
+        if (t.contains("uses-terminal")) {
+            target.custom_target.has_uses_terminal = true;
+            target.custom_target.uses_terminal = t.find("uses-terminal").as_boolean();
+        }
+
+        if (t.contains("command-expand-lists")) {
+            target.custom_target.has_command_expand_lists = true;
+            target.custom_target.command_expand_lists = t.find("command-expand-lists").as_boolean();
+        }
+
+        if (t.contains("custom-command")) {
+            const auto &custom_commands = t.find("custom-command");
+            if (!custom_commands.is_array()) {
+                throw_key_error("Expected an array of tables", "custom-command", custom_commands);
+            }
+            for (const auto &custom_command_value : custom_commands.as_array()) {
+                if (!custom_command_value.is_table()) {
+                    throw_key_error("Expected an array of tables", "custom-command", custom_command_value);
+                }
+
+                auto &custom = checker.create(custom_command_value);
+                Target::CustomCommand custom_command;
+
+                custom.optional("condition", custom_command.condition);
+
+                if (custom.contains("command")) {
+                    auto commands = parse_command_arguments(custom.find("command"), "command");
+                    for (auto &command : commands) {
+                        custom_command.commands.push_back(std::move(command));
+                    }
+                }
+
+                if (custom.contains("commands")) {
+                    auto commands = parse_command_arguments(custom.find("commands"), "commands");
+                    for (auto &command : commands) {
+                        custom_command.commands.push_back(std::move(command));
+                    }
+                }
+
+                custom.optional("outputs", custom_command.outputs);
+
+                if (custom.contains("build-event")) {
+                    custom_command.build_event = normalize_build_event(custom.find("build-event").as_string());
+                }
+
+                if (custom.contains("append")) {
+                    custom_command.has_append = true;
+                    custom_command.append = custom.find("append").as_boolean();
+                }
+
+                if (custom.contains("main-dependency")) {
+                    custom_command.has_main_dependency = true;
+                    custom_command.main_dependency = custom.find("main-dependency").as_string();
+                }
+
+                custom.optional("depends", custom_command.depends);
+                custom.optional("byproducts", custom_command.byproducts);
+
+                if (custom.contains("implicit-depends")) {
+                    custom_command.implicit_depends = parse_implicit_dependencies(custom.find("implicit-depends"), "implicit-depends");
+                }
+
+                if (custom.contains("working-directory")) {
+                    custom_command.has_working_directory = true;
+                    custom_command.working_directory = custom.find("working-directory").as_string();
+                }
+
+                if (custom.contains("comment")) {
+                    custom_command.has_comment = true;
+                    custom_command.comment = custom.find("comment").as_string();
+                }
+
+                if (custom.contains("depfile")) {
+                    custom_command.has_depfile = true;
+                    custom_command.depfile = custom.find("depfile").as_string();
+                }
+
+                if (custom.contains("job-pool")) {
+                    custom_command.has_job_pool = true;
+                    custom_command.job_pool = custom.find("job-pool").as_string();
+                }
+
+                if (custom.contains("job-server-aware")) {
+                    custom_command.has_job_server_aware = true;
+                    custom_command.job_server_aware = custom.find("job-server-aware").as_boolean();
+                }
+
+                if (custom.contains("verbatim")) {
+                    custom_command.has_verbatim = true;
+                    custom_command.verbatim = custom.find("verbatim").as_boolean();
+                }
+
+                if (custom.contains("uses-terminal")) {
+                    custom_command.has_uses_terminal = true;
+                    custom_command.uses_terminal = custom.find("uses-terminal").as_boolean();
+                }
+
+                if (custom.contains("codegen")) {
+                    custom_command.has_codegen = true;
+                    custom_command.codegen = custom.find("codegen").as_boolean();
+                }
+
+                if (custom.contains("command-expand-lists")) {
+                    custom_command.has_command_expand_lists = true;
+                    custom_command.command_expand_lists = custom.find("command-expand-lists").as_boolean();
+                }
+
+                if (custom.contains("depends-explicit-only")) {
+                    custom_command.has_depends_explicit_only = true;
+                    custom_command.depends_explicit_only = custom.find("depends-explicit-only").as_boolean();
+                }
+
+                if (custom_command.is_output_form() == custom_command.is_target_form()) {
+                    throw_key_error("Specify exactly one of outputs or build-event", "custom-command", custom_command_value);
+                }
+
+                if (custom_command.is_target_form()) {
+                    if (custom_command.build_event != "PRE_BUILD" && custom_command.build_event != "PRE_LINK" &&
+                        custom_command.build_event != "POST_BUILD") {
+                        throw_key_error("build-event must be one of: pre-build, pre-link, post-build", "build-event", custom.find("build-event"));
+                    }
+                    if (resolved_target_type == target_interface) {
+                        throw_key_error("build-event cannot be used with type = \"interface\"", "build-event", custom.find("build-event"));
+                    }
+                    if (resolved_target_type == target_custom && custom_command.build_event == "PRE_LINK") {
+                        throw_key_error("build-event = \"pre-link\" cannot be used with type = \"custom\"", "build-event",
+                                        custom.find("build-event"));
+                    }
+                    if (custom_command.has_append || custom_command.has_main_dependency || !custom_command.depends.empty() ||
+                        !custom_command.implicit_depends.empty() || custom_command.has_depfile || custom_command.has_job_pool ||
+                        custom_command.has_job_server_aware || custom_command.has_codegen || custom_command.has_depends_explicit_only) {
+                        throw_key_error("Unsupported option for TARGET custom commands", "custom-command", custom_command_value);
+                    }
+                } else {
+                    if (custom_command.has_depfile && !custom_command.implicit_depends.empty()) {
+                        throw_key_error("depfile cannot be used with implicit-depends", "depfile", custom.find("depfile"));
+                    }
+                    if (custom_command.has_job_pool && custom_command.has_uses_terminal && custom_command.uses_terminal) {
+                        throw_key_error("job-pool cannot be used with uses-terminal", "job-pool", custom.find("job-pool"));
+                    }
+                    if (custom_command.append &&
+                        (custom_command.has_depfile || custom_command.has_job_pool || custom_command.has_job_server_aware ||
+                         custom_command.has_codegen || custom_command.has_command_expand_lists || custom_command.has_uses_terminal ||
+                         custom_command.has_verbatim || custom_command.has_depends_explicit_only || !custom_command.byproducts.empty())) {
+                        throw_key_error("append cannot be used with depfile, job-pool, job-server-aware, codegen, command-expand-lists, "
+                                        "uses-terminal, verbatim, depends-explicit-only, or byproducts",
+                                        "append", custom.find("append"));
+                    }
+                }
+
+                if (custom_command.is_output_form() && custom_command.append && custom_command.commands.empty() && custom_command.depends.empty()) {
+                    throw_key_error("append requires at least one command or depends", "append", custom.find("append"));
+                }
+
+                if (custom_command.commands.empty() &&
+                    !(custom_command.is_output_form() && custom_command.append && !custom_command.depends.empty())) {
+                    throw_key_error("At least one command is required", "custom-command", custom_command_value);
+                }
+
+                target.custom_commands.push_back(std::move(custom_command));
+            }
+        }
+
+        if (resolved_target_type == target_custom && target.custom_target.has_job_pool && target.custom_target.has_uses_terminal &&
+            target.custom_target.uses_terminal) {
+            throw_key_error("job-pool cannot be used with uses-terminal", "job-pool", t.find("job-pool"));
+        }
+
+        if (resolved_target_type != target_custom && !target.custom_target.empty()) {
+            const char *custom_key = "all";
+            if (target.custom_target.has_command) {
+                custom_key = "command";
+            } else if (target.custom_target.has_commands) {
+                custom_key = "commands";
+            } else if (!target.custom_target.depends.empty()) {
+                custom_key = "depends";
+            } else if (!target.custom_target.byproducts.empty()) {
+                custom_key = "byproducts";
+            } else if (target.custom_target.has_working_directory) {
+                custom_key = "working-directory";
+            } else if (target.custom_target.has_comment) {
+                custom_key = "comment";
+            } else if (target.custom_target.has_job_pool) {
+                custom_key = "job-pool";
+            } else if (target.custom_target.has_job_server_aware) {
+                custom_key = "job-server-aware";
+            } else if (target.custom_target.has_verbatim) {
+                custom_key = "verbatim";
+            } else if (target.custom_target.has_uses_terminal) {
+                custom_key = "uses-terminal";
+            } else if (target.custom_target.has_command_expand_lists) {
+                custom_key = "command-expand-lists";
+            }
+            throw_key_error("Custom target options can only be used with type = \"custom\"", custom_key, t.find(custom_key));
+        }
+
         Condition<std::string> msvc_runtime;
         t.optional("msvc-runtime", msvc_runtime);
         for (const auto &cond_itr : msvc_runtime) {

tests/CMakeLists.txt

@@ -131,3 +131,33 @@ add_test(
 		"$<TARGET_FILE:cmkr>"
 		build
 )
+
+add_test(
+	NAME
+		custom-command
+	WORKING_DIRECTORY
+		"${CMAKE_CURRENT_LIST_DIR}/custom-command"
+	COMMAND
+		"$<TARGET_FILE:cmkr>"
+		build
+)
+
+add_test(
+	NAME
+		generator-executable
+	WORKING_DIRECTORY
+		"${CMAKE_CURRENT_LIST_DIR}/generator-executable"
+	COMMAND
+		"$<TARGET_FILE:cmkr>"
+		build
+)
+
+add_test(
+	NAME
+		protobuf
+	WORKING_DIRECTORY
+		"${CMAKE_CURRENT_LIST_DIR}/protobuf"
+	COMMAND
+		"$<TARGET_FILE:cmkr>"
+		build
+)

tests/cmake.toml

@@ -71,3 +71,21 @@ name = "objective-c"
 working-directory = "objective-c"
 command = "$<TARGET_FILE:cmkr>"
 arguments = ["build"]
+
+[[test]]
+name = "custom-command"
+working-directory = "custom-command"
+command = "$<TARGET_FILE:cmkr>"
+arguments = ["build"]
+
+[[test]]
+name = "generator-executable"
+working-directory = "generator-executable"
+command = "$<TARGET_FILE:cmkr>"
+arguments = ["build"]
+
+[[test]]
+name = "protobuf"
+working-directory = "protobuf"
+command = "$<TARGET_FILE:cmkr>"
+arguments = ["build"]

tests/custom-command/cmake.toml

@@ -0,0 +1,123 @@
+# This test demonstrates add_custom_command and add_custom_target support in cmkr.
+#
+# There are two forms of add_custom_command in CMake:
+# 1. Output form: generates files that can be consumed by other targets
+# 2. Target form: runs commands at build time for a specific target (pre-build, pre-link, post-build)
+
+[project]
+name = "custom-command"
+description = "Tests add_custom_command and add_custom_target support"
+
+# -----------------------------------------------------------------------------
+# Simple executable demonstrating post-build events
+# -----------------------------------------------------------------------------
+
+[target.hello]
+type = "executable"
+sources = ["src/hello.cpp"]
+
+# This post-build command runs after the 'hello' executable is built.
+# build-event can be: "pre-build", "pre-link", or "post-build"
+[[target.hello.custom-command]]
+build-event = "post-build"
+command = ["${CMAKE_COMMAND}", "-E", "echo", "Built executable: $<TARGET_FILE_NAME:hello>"]
+comment = "Print the built executable name"
+
+# -----------------------------------------------------------------------------
+# Executable with code generation (output form custom command)
+# -----------------------------------------------------------------------------
+
+[target.custom-command]
+type = "executable"
+sources = ["src/main.cpp"]
+include-directories = ["${CMAKE_CURRENT_BINARY_DIR}/generated"]
+
+# Output form: This custom command generates source files before building.
+# Relative outputs follow CMake and are interpreted from the binary directory.
+# The outputs are automatically added as sources to the target.
+[[target.custom-command.custom-command]]
+outputs = ["generated/generated.cpp"]
+byproducts = ["generated/generated.hpp"]
+depends = ["cmake/generate_source.cmake"]
+command = [
+    "${CMAKE_COMMAND}",
+    "-DOUTPUT_CPP=${CMAKE_CURRENT_BINARY_DIR}/generated/generated.cpp",
+    "-DOUTPUT_HPP=${CMAKE_CURRENT_BINARY_DIR}/generated/generated.hpp",
+    "-P",
+    "${CMAKE_CURRENT_SOURCE_DIR}/cmake/generate_source.cmake",
+]
+comment = "Generate source files"
+verbatim = true
+
+# Target form: This post-build command runs after 'custom-command' is built.
+[[target.custom-command.custom-command]]
+build-event = "post-build"
+command = [
+    "${CMAKE_COMMAND}",
+    "-E",
+    "touch",
+    "${CMAKE_CURRENT_BINARY_DIR}/custom-command-post-build.stamp",
+]
+byproducts = ["${CMAKE_CURRENT_BINARY_DIR}/custom-command-post-build.stamp"]
+comment = "Create a post-build stamp file"
+verbatim = true
+
+# -----------------------------------------------------------------------------
+# Custom target (add_custom_target)
+# -----------------------------------------------------------------------------
+
+# A custom target runs commands independently of any executable/library.
+# Setting 'all = true' makes it run as part of the default build.
+[target.custom-codegen]
+type = "custom"
+all = true
+command = [
+    "${CMAKE_COMMAND}",
+    "-E",
+    "touch",
+    "${CMAKE_CURRENT_BINARY_DIR}/custom-target.stamp",
+]
+byproducts = ["${CMAKE_CURRENT_BINARY_DIR}/custom-target.stamp"]
+comment = "Run custom target"
+verbatim = true
+
+# -----------------------------------------------------------------------------
+# Template-based custom target
+# -----------------------------------------------------------------------------
+
+# Custom target options should also work when the target type comes from a template.
+[template.generated-custom-target]
+type = "custom"
+all = true
+verbatim = true
+
+[target.custom-codegen-template]
+type = "generated-custom-target"
+command = [
+    "${CMAKE_COMMAND}",
+    "-DINPUT=${CMAKE_CURRENT_BINARY_DIR}/template-custom-target.stamp",
+    "-P",
+    "${CMAKE_CURRENT_SOURCE_DIR}/cmake/verify_file_exists.cmake",
+]
+comment = "Verify the generated stamp exists"
+
+# The output-form custom command should automatically become a dependency of the
+# custom target, so the verification command sees the stamp file.
+[[target.custom-codegen-template.custom-command]]
+outputs = ["template-custom-target.stamp"]
+command = [
+    "${CMAKE_COMMAND}",
+    "-E",
+    "touch",
+    "${CMAKE_CURRENT_BINARY_DIR}/template-custom-target.stamp",
+]
+comment = "Create a stamp file for the template-based custom target"
+verbatim = true
+
+# A target-level all = false should override the template's all = true.
+# If this target is incorrectly included in the default build, the build fails.
+[target.custom-codegen-template-disabled]
+type = "generated-custom-target"
+all = false
+command = ["${CMAKE_COMMAND}", "-E", "false"]
+comment = "This target must not run as part of the default build"

tests/custom-command/cmake/generate_source.cmake

@@ -0,0 +1,13 @@
+if(NOT DEFINED OUTPUT_CPP)
+    message(FATAL_ERROR "OUTPUT_CPP is required")
+endif()
+
+if(NOT DEFINED OUTPUT_HPP)
+    message(FATAL_ERROR "OUTPUT_HPP is required")
+endif()
+
+get_filename_component(_output_dir "${OUTPUT_CPP}" DIRECTORY)
+file(MAKE_DIRECTORY "${_output_dir}")
+
+file(WRITE "${OUTPUT_HPP}" "#pragma once\n#define GENERATED_VALUE 42\n")
+file(WRITE "${OUTPUT_CPP}" "#include \"generated.hpp\"\nint generated_value() { return GENERATED_VALUE; }\n")

tests/custom-command/cmake/verify_file_exists.cmake

@@ -0,0 +1,9 @@
+if(NOT DEFINED INPUT)
+    message(FATAL_ERROR "INPUT is required")
+endif()
+
+if(NOT EXISTS "${INPUT}")
+    message(FATAL_ERROR "Expected file not found: ${INPUT}")
+endif()
+
+message(STATUS "Verified file exists: ${INPUT}")

tests/custom-command/src/hello.cpp

@@ -0,0 +1,6 @@
+#include <iostream>
+
+int main() {
+    std::cout << "Hello, world!" << std::endl;
+    return 0;
+}

tests/custom-command/src/main.cpp

@@ -0,0 +1,7 @@
+#include "generated.hpp"
+
+int generated_value();
+
+int main() {
+    return generated_value() == GENERATED_VALUE ? 0 : 1;
+}

tests/generator-executable/cmake.toml

@@ -0,0 +1,54 @@
+# This test demonstrates a common pattern: using an executable to generate sources
+# for another target. The generator runs at build time and produces code that is
+# consumed by the main executable.
+#
+# CMake handles the dependency automatically: the generator executable is built
+# first, then it runs to produce the generated sources, and finally the main
+# executable is built using those sources.
+
+[project]
+name = "generator-executable"
+description = "Tests using an executable to generate sources for another target"
+
+# -----------------------------------------------------------------------------
+# Generator executable: produces code at build time
+# -----------------------------------------------------------------------------
+
+[target.generate_numbers]
+type = "executable"
+sources = ["src/generate_numbers.cpp"]
+
+# Post-build: confirm the generator was built
+[[target.generate_numbers.custom-command]]
+build-event = "post-build"
+command = ["${CMAKE_COMMAND}", "-E", "echo", "Generator built successfully: $<TARGET_FILE_NAME:generate_numbers>"]
+comment = "Confirm generator executable was built"
+
+# -----------------------------------------------------------------------------
+# Main executable: uses generated sources
+# -----------------------------------------------------------------------------
+
+[target.main]
+type = "executable"
+sources = ["src/main.cpp"]
+include-directories = ["${CMAKE_CURRENT_BINARY_DIR}/generated"]
+
+# Create the generated directory before the generator runs.
+cmake-before = """
+file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/generated")
+"""
+
+# Output form custom command: runs the generate_numbers executable to generate sources.
+# The outputs are automatically added as sources to this target.
+# The DEPENDS on "generate_numbers" ensures the generator is built before this runs.
+[[target.main.custom-command]]
+outputs = ["${CMAKE_CURRENT_BINARY_DIR}/generated/numbers.cpp"]
+depends = ["generate_numbers"]
+command = ["$<TARGET_FILE:generate_numbers>", "${CMAKE_CURRENT_BINARY_DIR}/generated/numbers.cpp"]
+comment = "Run generate_numbers to generate numbers.cpp"
+
+# Post-build: run the executable to verify it works
+[[target.main.custom-command]]
+build-event = "post-build"
+command = ["$<TARGET_FILE:main>"]
+comment = "Run the main executable to verify generated code works"

tests/generator-executable/src/generate_numbers.cpp

@@ -0,0 +1,44 @@
+// Simple code generator that produces a C++ source file with a function
+// that returns a vector of numbers.
+
+#include <fstream>
+#include <iostream>
+#include <string>
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) {
+        std::cerr << "Usage: " << argv[0] << " <output_file>" << std::endl;
+        return 1;
+    }
+
+    std::string output_path = argv[1];
+
+    // The example ensures the output directory exists before invoking the generator.
+
+    std::ofstream out(output_path);
+    if (!out) {
+        std::cerr << "Failed to open: " << output_path << std::endl;
+        return 1;
+    }
+
+    out << "// Auto-generated by codegen - DO NOT EDIT\n";
+    out << "#include <vector>\n";
+    out << "#include <cstddef>\n";
+    out << "\n";
+    out << "std::vector<int> get_numbers() {\n";
+    out << "    return {";
+    for (int i = 1; i <= 10; ++i) {
+        if (i > 1)
+            out << ", ";
+        out << i * i; // 1, 4, 9, 16, 25, 36, 49, 64, 81, 100
+    }
+    out << "};\n";
+    out << "}\n";
+    out << "\n";
+    out << "std::size_t get_numbers_count() {\n";
+    out << "    return 10;\n";
+    out << "}\n";
+
+    std::cout << "Generated: " << output_path << std::endl;
+    return 0;
+}

tests/generator-executable/src/main.cpp

@@ -0,0 +1,26 @@
+// Main executable that uses the generated code
+
+#include <iostream>
+#include <vector>
+
+// Functions generated by codegen executable
+std::vector<int> get_numbers();
+std::size_t get_numbers_count();
+
+int main() {
+    std::cout << "Numbers from generated code:" << std::endl;
+
+    auto numbers = get_numbers();
+    for (std::size_t i = 0; i < numbers.size(); ++i) {
+        std::cout << "  numbers[" << i << "] = " << numbers[i] << std::endl;
+    }
+
+    // Verify the count
+    if (numbers.size() == get_numbers_count()) {
+        std::cout << "Success: Generated " << numbers.size() << " numbers!" << std::endl;
+        return 0;
+    } else {
+        std::cerr << "Error: Count mismatch!" << std::endl;
+        return 1;
+    }
+}

tests/protobuf/.gitignore

@@ -0,0 +1,2 @@
+build/
+*.bin

tests/protobuf/cmake.toml

@@ -0,0 +1,81 @@
+# This test demonstrates using protobuf with cmkr for code generation.
+#
+# The example:
+# 1. Fetches protobuf from GitHub using FetchContent
+# 2. Uses a custom command to generate C++ sources from a .proto file
+# 3. Links an executable against the generated sources and protobuf library
+# 4. Serializes and deserializes a simple message
+#
+# Note: protobuf v21.x is used because newer versions (v22+) require abseil-cpp
+# as a dependency, which significantly complicates the build.
+
+[cmake]
+version = "3.18...3.31"
+
+[project]
+name = "protobuf-example"
+description = "Demonstrates protobuf integration with cmkr custom commands"
+
+# -----------------------------------------------------------------------------
+# Fetch protobuf from GitHub
+# Using v21.12 (last version before abseil-cpp became required)
+# -----------------------------------------------------------------------------
+
+[fetch-content.protobuf]
+git = "https://github.com/protocolbuffers/protobuf"
+tag = "v21.12"
+options = {
+  protobuf_BUILD_TESTS = false,
+  protobuf_BUILD_EXAMPLES = false,
+  protobuf_BUILD_LIBPROTOC = false,
+  protobuf_BUILD_SHARED_LIBS = false,
+  protobuf_MSVC_STATIC_RUNTIME = false,
+  SKIP_INSTALL_ALL = true,
+  protobuf_WITH_ZLIB = false,
+}
+
+# -----------------------------------------------------------------------------
+# Main executable using protobuf
+# -----------------------------------------------------------------------------
+
+[target.protobuf_example]
+type = "executable"
+sources = [
+    "src/main.cpp",
+]
+include-directories = [
+    "${CMAKE_CURRENT_BINARY_DIR}/generated",
+]
+link-libraries = ["protobuf::libprotobuf"]
+compile-features = ["cxx_std_17"]
+
+# Create the generated directory before running protoc
+cmake-before = """
+file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/generated")
+"""
+
+# Custom command to generate C++ sources from .proto file
+# This uses protoc from the fetched protobuf repository
+[[target.protobuf_example.custom-command]]
+outputs = [
+    "${CMAKE_CURRENT_BINARY_DIR}/generated/addressbook.pb.h",
+    "${CMAKE_CURRENT_BINARY_DIR}/generated/addressbook.pb.cc",
+]
+depends = [
+    "${CMAKE_CURRENT_SOURCE_DIR}/proto/addressbook.proto",
+    "protobuf::protoc",  # Ensure protoc is built first
+]
+command = [
+    "$<TARGET_FILE:protobuf::protoc>",
+    "--cpp_out=${CMAKE_CURRENT_BINARY_DIR}/generated",
+    "-I${CMAKE_CURRENT_SOURCE_DIR}/proto",
+    "${CMAKE_CURRENT_SOURCE_DIR}/proto/addressbook.proto",
+]
+comment = "Generate C++ sources from addressbook.proto"
+verbatim = true
+
+# Post-build: run the executable to verify it works
+[[target.protobuf_example.custom-command]]
+build-event = "post-build"
+command = ["$<TARGET_FILE:protobuf_example>"]
+comment = "Run protobuf_example to verify serialization/deserialization works"

tests/protobuf/proto/addressbook.proto

@@ -0,0 +1,31 @@
+// A simple address book example demonstrating protobuf serialization.
+// Based on the official protobuf tutorial example.
+
+syntax = "proto3";
+
+package tutorial;
+
+// A person with basic contact information
+message Person {
+  string name = 1;
+  int32 id = 2;
+  string email = 3;
+
+  enum PhoneType {
+    MOBILE = 0;
+    HOME = 1;
+    WORK = 2;
+  }
+
+  message PhoneNumber {
+    string number = 1;
+    PhoneType type = 2;
+  }
+
+  repeated PhoneNumber phones = 4;
+}
+
+// An address book containing multiple people
+message AddressBook {
+  repeated Person people = 1;
+}

tests/protobuf/src/main.cpp

@@ -0,0 +1,146 @@
+// Protobuf serialization/deserialization example
+// This demonstrates using protobuf with cmkr for code generation
+
+#include <iostream>
+#include <fstream>
+#include <string>
+#include "addressbook.pb.h"
+
+// Creates a sample address book with some people
+void create_address_book(tutorial::AddressBook &book) {
+    // Add first person
+    tutorial::Person *person1 = book.add_people();
+    person1->set_name("Alice Smith");
+    person1->set_id(1);
+    person1->set_email("alice@example.com");
+
+    // Add phone numbers for Alice
+    tutorial::Person::PhoneNumber *phone1 = person1->add_phones();
+    phone1->set_number("555-1234");
+    phone1->set_type(tutorial::Person::HOME);
+
+    tutorial::Person::PhoneNumber *phone2 = person1->add_phones();
+    phone2->set_number("555-5678");
+    phone2->set_type(tutorial::Person::WORK);
+
+    // Add second person
+    tutorial::Person *person2 = book.add_people();
+    person2->set_name("Bob Johnson");
+    person2->set_id(2);
+    person2->set_email("bob@example.com");
+
+    tutorial::Person::PhoneNumber *phone3 = person2->add_phones();
+    phone3->set_number("555-9999");
+    phone3->set_type(tutorial::Person::MOBILE);
+}
+
+// Prints the contents of an address book
+void print_address_book(const tutorial::AddressBook &book) {
+    std::cout << "Address Book (" << book.people_size() << " people):\n";
+    std::cout << "==========================================\n\n";
+
+    for (int i = 0; i < book.people_size(); ++i) {
+        const tutorial::Person &person = book.people(i);
+
+        std::cout << "Person ID: " << person.id() << "\n";
+        std::cout << "  Name: " << person.name() << "\n";
+        std::cout << "  Email: " << person.email() << "\n";
+
+        for (int j = 0; j < person.phones_size(); ++j) {
+            const tutorial::Person::PhoneNumber &phone = person.phones(j);
+            std::cout << "  Phone #" << (j + 1) << ": " << phone.number() << " (";
+
+            switch (phone.type()) {
+            case tutorial::Person::MOBILE:
+                std::cout << "mobile";
+                break;
+            case tutorial::Person::HOME:
+                std::cout << "home";
+                break;
+            case tutorial::Person::WORK:
+                std::cout << "work";
+                break;
+            default:
+                std::cout << "unknown";
+            }
+            std::cout << ")\n";
+        }
+        std::cout << "\n";
+    }
+}
+
+int main() {
+    // Verify that the version of the library that we linked against is
+    // compatible with the version of the headers we compiled against.
+    GOOGLE_PROTOBUF_VERIFY_VERSION;
+
+    std::cout << "Protobuf cmkr Example\n";
+    std::cout << "=====================\n\n";
+
+    // Create an address book
+    tutorial::AddressBook original_book;
+    create_address_book(original_book);
+
+    std::cout << "Original Address Book:\n";
+    print_address_book(original_book);
+
+    // Serialize to string
+    std::string serialized;
+    if (!original_book.SerializeToString(&serialized)) {
+        std::cerr << "Error: Failed to serialize address book\n";
+        return 1;
+    }
+    std::cout << "Serialized size: " << serialized.size() << " bytes\n\n";
+
+    // Deserialize into a new object
+    tutorial::AddressBook deserialized_book;
+    if (!deserialized_book.ParseFromString(serialized)) {
+        std::cerr << "Error: Failed to deserialize address book\n";
+        return 1;
+    }
+
+    std::cout << "Deserialized Address Book:\n";
+    print_address_book(deserialized_book);
+
+    // Write to file
+    const char *filename = "addressbook.bin";
+    {
+        std::ofstream output(filename, std::ios::binary);
+        if (!original_book.SerializeToOstream(&output)) {
+            std::cerr << "Error: Failed to write to file\n";
+            return 1;
+        }
+    }
+    std::cout << "Written to file: " << filename << "\n";
+
+    // Read back from file
+    tutorial::AddressBook file_book;
+    {
+        std::ifstream input(filename, std::ios::binary);
+        if (!file_book.ParseFromIstream(&input)) {
+            std::cerr << "Error: Failed to read from file\n";
+            return 1;
+        }
+    }
+    std::cout << "Read back from file successfully!\n\n";
+
+    // Verify all three versions are identical
+    bool all_match = true;
+    if (original_book.SerializeAsString() != deserialized_book.SerializeAsString()) {
+        std::cerr << "Error: Original and deserialized don't match!\n";
+        all_match = false;
+    }
+    if (original_book.SerializeAsString() != file_book.SerializeAsString()) {
+        std::cerr << "Error: Original and file don't match!\n";
+        all_match = false;
+    }
+
+    if (all_match) {
+        std::cout << "SUCCESS: All serialization methods produced identical results!\n";
+    }
+
+    // Clean up any global objects allocated by protobuf
+    google::protobuf::ShutdownProtobufLibrary();
+
+    return all_match ? 0 : 1;
+}